blit_setup(): Screen depth 15 not supported!

when I opened framebuffer with ARGB8888,then run the sample ./simpledecoration -wqs,the program run well.
but when I opened framebuffer with ARGB1555,run the sample ./simpledecoration -wqs again,
got the following error:
blit_setup(): Screen depth 15 not supported!
Aborted

I changed the -depths to -depths all,and configured again, the same error.
I even changed the qscreenlinuxfb_qws.cpp. change QScreen::setPixelFormat(format) to
QScreen::setPixelFormat(QImage::Format_RGB16),stil l got the same error.
the Qt version is 4.8.2

why? Thanks a lot.
Forest

Most likely the framebuffer doesn't support 15 bit displays.

I cat the fb info.
cat /proc/graphics/hifb1
layer name :layer_1
Open count :2
Show state :ON
Start position (0, 0)
xres, yres (1280, 720)
xres_virtual, yres_virtual (1280, 1440)
xoffset, yoffset (0, 0)
fix.line_length :2560
Mem size: :8100 KB
Layer Scale (hw): :NO
ColorFormat: :ARGB1555
Alpha Enable :ON
AlphaChannel Enable :OFF
Alpha0, Alpha1 :255, 255
Alpha Global :128
Colorkey Enable :OFF
Colorkey value :0x0
Deflicker Mode: :NONE
Deflicker Level: :AUTO
Display Buffer mode :unkown
Displaying addr (register) :0x9092f000
display buffer[0] addr :0x9092f000
display buffer[1] addr :0x90af1000
displayrect (1280, 720)
screenrect (1280, 720)
device max resolution :1280, 720
IsNeedFlip(2buf) :NO
BufferIndexDisplaying(2buf) :0
refresh request num(2buf) :0
switch buf num(2buf) :0
union rect (2buf) (0,0,0,0)
canavas updated addr :0x9092f000
canavas updated (w, h) :1280,720
canvas width :1280
canvas height :720
canvas pitch :2560
canvas format :ARGB1555
IsCompress :NO

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Added after 38 minutes:

Quote:

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Originally Posted by wysota

Most likely the framebuffer doesn't support 15 bit displays.

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Thanks,how to see whether the framebuffer support 15bit displays?
actually,I want to use ARGB1555,which is 16 bit.

Quote:

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Originally Posted by Forest

actually,I want to use ARGB1555,which is 16 bit.

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Apparently the frame buffer thinks differently. Consult your framebuffer manual.

Quote:

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Originally Posted by wysota

Apparently the frame buffer thinks differently. Consult your framebuffer manual.

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The framebuffer only support ARGB8888 and ARGB1555,I tried setting QT to RGB565(force d=16 in qscreenlinuxfb_qws.cpp),the error disappeared,but the output color was strange.
How to set QT use ARGB1555?

Hmm... how exactly did you try setting the framebuffer into ARGB1555 in Qt? As far as I can see such format is not supported by Qt.

Quote:

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Originally Posted by wysota

Hmm... how exactly did you try setting the framebuffer into ARGB1555 in Qt? As far as I can see such format is not supported by Qt.

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hi,wysota,thanks for your help.I can not set the framebuffer into ARGB1555 in Qt.Such format is not supported by Qt,really?
but I find the format in qscreenlinuxfb_qws.cpp.
void QLinuxFbScreen::setPixelFormat(struct fb_var_screeninfo info)
{
const fb_bitfield rgba[4] = { info.red, info.green,
info.blue, info.transp };

QImage::Format format = QImage::Format_Invalid;

switch (d) {
case 15: {
const fb_bitfield rgb1555[4] = {{10, 5, 0}, {5, 5, 0},
{0, 5, 0}, {15, 1, 0}};
const fb_bitfield bgr1555[4] = {{0, 5, 0}, {5, 5, 0},
{10, 5, 0}, {15, 1, 0}};
if (memcmp(rgba, rgb1555, 3 * sizeof(fb_bitfield)) == 0) {
format = QImage::Format_RGB555;
} else if (memcmp(rgba, bgr1555, 3 * sizeof(fb_bitfield)) == 0) {
format = QImage::Format_RGB555;
pixeltype = QScreen::BGRPixel;
}
break;
}
QScreen::setPixelFormat(format);
}

we can see,Qt treats ARGB1555 as Format_RGB555.

And apparently it tries to set that as the framebuffer format, giving you 15 bits which is not supported by your hardware. It looks like either a bug in Qt, your code or in the driver.